Using module 'subprocess' with timeout

I don't know much about the low level details; but, given that inpython 2.6 the API offers the ability to wait for threads andterminate processes, what about running the process in a separatethread?

import subprocess, threadingclass Command(object):    def __init__(self, cmd):        self.cmd = cmd        self.process = None    def run(self, timeout):        def target():            print 'Thread started'            self.process = subprocess.Popen(self.cmd, shell=True)            self.process.communicate()            print 'Thread finished'        thread = threading.Thread(target=target)        thread.start()        thread.join(timeout)        if thread.is_alive():            print 'Terminating process'            self.process.terminate()            thread.join()        print self.process.returncodecommand = Command("echo 'Process started'; sleep 2; echo 'Process finished'")command.run(timeout=3)command.run(timeout=1)

The output of this snippet in my machine is:

Thread startedProcess startedProcess finishedThread finished0Thread startedProcess startedTerminating processThread finished-15

where it can be seen that, in the first execution, the processfinished correctly (return code 0), while the in the second one theprocess was terminated (return code -15).

I haven't tested in windows; but, aside from updating the examplecommand, I think it should work since I haven't found in thedocumentation anything that says that thread.join or process.terminateis not supported.

In Python 3.3+:

from subprocess import STDOUT, check_outputoutput = check_output(cmd, stderr=STDOUT, timeout=seconds)

output is a byte string that contains command's merged stdout, stderr data.

check_output raises CalledProcessError on non-zero exit status as specified in the question's text unlike proc.communicate() method.

I've removed shell=True because it is often used unnecessarily. You can always add it back if cmd indeed requires it. If you add shell=True i.e., if the child process spawns its own descendants; check_output() can return much later than the timeout indicates, see Subprocess timeout failure.

The timeout feature is available on Python 2.x via the subprocess32 backport of the 3.2+ subprocess module.

jcollado's answer can be simplified using the threading.Timer class:

import shlexfrom subprocess import Popen, PIPEfrom threading import Timerdef run(cmd, timeout_sec):    proc = Popen(shlex.split(cmd), stdout=PIPE, stderr=PIPE)    timer = Timer(timeout_sec, proc.kill)    try:        timer.start()        stdout, stderr = proc.communicate()    finally:        timer.cancel()# Examples: both take 1 secondrun("sleep 1", 5)  # process ends normally at 1 secondrun("sleep 5", 1)  # timeout happens at 1 second